/Engine/Source/Runtime/MovieScene/Public/Channels/MovieSceneChannelData.h
Add a new key at a given time
The index of the newly added key
int32 AddKey ( [FFrameNumber](API\Runtime\Core\Misc\FFrameNumber) InTime, [ParamType](API\Runtime\MovieScene\Channels\TMovieSceneChannelData\ParamType) InValue )